What is R.I.S.E.?
R.I.S.E., which stands for Realistic Image Synthesis Engine is a state of the art engine and framework for the simulation and realistic image synthesis of natural phenomenon based on physics, biology and chemistry.
What R.I.S.E. is not.
R.I.S.E. is not meant to be a competitor to commercially avaiable ray tracing engines such as Brazil, finalRender, or v-ray. It is definitely not meant to be a competitor to scanline renderers or micro-polygon tesselating engines such as Pixar's RenderMan. R.I.S.E. is not meant to be a tool to be used by a studio to produce content for time-critical projects. It is not meant to be an alternative to other open source renderers such as Aqsis, Pixie or POVRay.
Who is R.I.S.E. for?
R.I.S.E. is primarily intended for researchers involved in the simulation of natural phenomenon. However, artists should be able to use R.I.S.E. to generate compelling images as long as they aren't afraid to get their hands a little dirty (and have massive CPU cycles to spare).

Another primary focus of R.I.S.E. is to provide code that is lucid, readible and correct so that people who want to learn the fundamentals of physically-based rendering and ray tracing have something to learn from.http://rise.sourceforge.net